1. Field of the Invention
The present invention relates to ink jet recording devices and ink cartridges. Particularly, the present invention relates to an ink jet recording device with a detachable ink cartridge and the ink cartridge thereof.
2. Description of the Background Art
An ink jet recording device has a disadvantage that the device is contaminated due to exudation of liquid ink used therein. Various devices are implemented as to a means of preventing ink from seeping out. For the purpose of preventing ink exudation particularly when exchanging an ink cartridge, an open/close device is provided at the ink supply path of the ink cartridge coupling portion at the recording head side. The open/close device is open under the state where the ink cartridge is coupled, and closed just before the ink cartridge is detached.
Referring to FIGS. 1 and 2, a conventional ink jet recording device with a detachable ink cartridge disclosed in Japanese Patent Laying-Open No. 60-36174 will be described hereinafter.
Referring to FIG. 1, an ink jet recording device includes a medium to be recorded on (referred to as "recording sheet" hereinafter) 101, a platen 102 driven by a driving source such as a pulse motor not shown to convey recording sheet 101, a recording device main body 121 for discharging ink onto recording sheet 101 to record information, and an ink cassette 107 for supplying ink to the recording device main body 121.
The recording device main body 121 includes an ink jet head unit 103 to discharge ink onto recording sheet 101 for printing, a first tube 104 for supplying ink to ink jet head unit 103, and a joint unit 105 for attaching/detaching ink cassette 107 and recording device main body 121.
Ink jet head unit 103 includes a head unit 103A for discharging ink onto recording sheet 101, and a sub tank 103B for supplying ink to head unit 103A. Ink 103C is accommodated in sub tank 103B.
Referring to FIG. 2, joint unit 105 includes a support unit 110 fixed to recording device main body 121, a second tube 108 of sufficient elasticity, connected to first tube 104 and fixed to support unit 110, a third tube 109 connected to second tube 108, a shaft 112 fixed to recording device main body 121, a lever 111 fitted to shaft 112 to press and block second tube 108 by the elasticity of spring 113, and a pin 106 inserted into third tube 109 and protruding from joint portion 105.
Ink cassette 107 includes a main body 116, an ink tank 118 provided within main body 116 and located several inches below head unit 103A, a tube 117 connected to ink tank 118, and a coupling portion 115 formed of an elastic material such as silicon rubber, connected to tube 117, and coupled to recording device main body 121 by having a pin 106 inserted therein.
Coupling portion 115 includes an ink passage 114 into which pin 106 is inserted for supplying ink.
A claw 111A abutting against a chamfered portion 107A provided at ink cassette 107, and a claw 111B urged against second tube 108 are provided at lever 111. Ink tank 118 is constituted of a flexible material formed by vapor-depositing aluminum on a laminate film, for example.
Since ink tank 118 is flexible and the interior thereof is at atmospheric pressure, the leading end of head 103A is maintained under a slight negative pressure. This prevents ink from leaking from the end of the head. When ink is discharged from head 103A by mechanical force such as a drive by a piezo-electric element, ink tank 118 is deformed according to reduction of ink to supply an appropriate amount of ink to head 103A.
When ink tank 118 becomes empty, ink cannot be discharged from head 103A even if ink remains in sub tank 103B or tube 108. On this occasion, ink cassette 107 must be exchanged. By lifting ink cassette 107 in the direction of arrow X in FIG. 2, claw 111A is detached from cassette 107 with a shifted distance of L2. In response, lever 111 is turned counterclockwise about shaft 112 by spring 113. The tip of claw 111B is urged against tube 108 in the direction of arrow P. Tube 108 is squeezed at the contact point with claw 111B, whereby the ink supply path formed by tube 108 is sealed. Here, a small amount of ink within tube 8 is shifted towards ink passage 114 via pin 106. However, the coupling between ink tank 118 and pin 106 is still maintained since length L1 of pin 106 is L1&gt;L2, so that the ink will not flow backwards outside ink cassette 107 to contaminate the device.
Ink also flows towards the direction of head 103A. However, the provision of a cap device and the like at head 103A prevents ink leakage in the opposite direction. Ink cassette 107 is further moved to be detached from device main body 121, and pin 106 is drawn out from cassette 107. Since tube 108 is sealed by claw 111B, ink will not leak out from tube 108.
The elastic body such as of rubber forming coupling portion 115 has its elastic deformation restored immediately when pin 106 is pulled out. Ink will not leak from ink cassette 107 since coupling portion 117 is sealed. More specifically, the record liquid supply path connecting the recording head and a recording liquid reservoir chamber is blocked just before ink cassette 107 is detached. Thus, ink will not leak.
When ink cassette 107 is inserted into recording device main body in a direction opposite to arrow X, lever 111 is turned clockwise against the force of spring 113 by virtue of chamfered portion 107A of cassette 107, whereby tube 108 is unblocked. Pin 106 pierces the elastic body of rubber forming coupling portion 115 to provide communication with tube 117 in ink cassette 107. Thus, the recording liquid supply path is open under the state where the recording head and the recording liquid reservoir chamber are connected.
The above-described conventional device has an ink supply path open/close device of a mechanism that seals the supply path by squeezing an elastic tube with the claw portion of an open/close lever. An ink tank formed by vapor-depositing aluminum onto a laminate film in which ink is sealed is provided in the ink cartridge.
The interior of the tank is completely sealed, and suction is required according to a slight negative pressure to supply ink outwards.
As joining means of an ink cartridge in the above-described conventional device, a plug member formed of silicon rubber at the ink cartridge side is urged against the connecting portion (pin) of the head side, whereby the plug member is pierced to be coupled with the tube member within the ink tank.
Simultaneous to this operation, the open/close lever blocking the ink supply path at the head side abuts against the ink cartridge to be turned. The blocking is removed to provide communication of ink in the ink tank and the recording head. Here, the interior of the ink tank is maintained at a pressure not higher than atmospheric pressure to prevent exudation of ink from the nozzle portion of the head.
Since the ink supply path is opened/closed by squeezing an elastic tube with an open/close device in such a conventional ink jet recording device, there is a problem that a crack is generated in the tube when the ink cartridge is frequently exchanged, undesirable from the standpoint of reliability.
The open/close device is opened after the coupling between the ink cartridge and the ink jet recording device main body is completed, and closed just before the ink cartridge is detached from the main body of the ink jet recording device. Therefore, there is a possibility that a bubble in the ink supply path of the coupling portion is urged into the ink cartridge. There is also a possibility that discharge of accumulated bubbles in the ink supply path of the coupling portion is not sufficient. Supply of ink from the ink cartridge to the main body of the ink jet recording device may be deteriorated by such bubbles.
There is also a problem that ink cannot be supplied sufficiently since the opening of piercing the member sealing the connection portion of the ink cartridge with a pin is small.
Furthermore, a great amount of the accumulated bubbles in the coupling portion in the state where the ink cartridge is coupled to the ink jet recording device enters the ink cartridge to degrade or completely stop supply of ink.